Hybrid electric vehicles (HEV's), plug-in hybrid electric vehicles (PHEV's), battery electric vehicles (BEV's), fuel cell vehicles and other known electrified vehicles differ from conventional motor vehicles in that they are powered by one or more electric machines (i.e., electric motors and/or generators) instead of or in addition to an internal combustion engine. High voltage current for powering these types of electric machine(s) is typically supplied by a traction battery system having one or more battery cells that store energy.
Battery systems are typically constructed of one or more battery modules that each includes a plurality of battery cells. In some conditions, heat is generated in the battery cells. This heat may need to be removed to improve battery cell capacity, life and performance. The battery cells may alternatively need heated in order to function properly in other conditions, such as extremely cold ambient conditions.